Recent studies indicate that dementing disorders occurring in individuals with Lewy bodies (LB), including Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB), comprise the second most common dementia subgroup after Alzheimer's disease (AD). Despite the common presence of cognitive impairment and Parkinsonism in both groups, there is a lack of understanding regarding the relationship between PDD and DLB. A recent international workshop on DLB and PDD in Newcastle, UK brought scientists together to revise diagnostic criteria for DLB; they underscored the need to work toward defining the relationship between PDD and DLB, and to identify better biomarkers for the Lewy body disorders. The purpose of the proposed conference is to have internationally recognized scientists from a variety of backgrounds define areas of agreement and controversy regarding the relationship between PDD and DLB. The date (February 21-22, 2006) was selected to mesh with the World Parkinson Congress (WPC) which will be held in Washington, DC starting the evening of February 22nd. The conference, with a targeted audience including both professionals and caregivers, will involve two days of lectures and breakout group discussions with equal representation of speakers from PDD and DLB backgrounds. At the end of day two there will be a final group discussion where points of agreement and areas needing additional focus are identified. An executive group will then prepare a statement for publication summarizing the highlighted points. Clarifying the relationship between PDD and DLB is relevant to public health because these patients comprise a large segment of our aging population. Our approach to developing strategies for management, treatment and prevention for the LB disorders is likely to differ depending on whether PDD and DLB fundamentally represent one disorder with different clinical presentations or separate disease entities. [unreadable] [unreadable]